Fuel cells transform chemical energy to electrical energy by reacting gas in the presence of an electrolyte, electrodes and a catalyst. A catalyst may be platinum or an expensive material. Consequently, it is desirable to use as little catalyst as possible.
Fuel cells are often used to generate electricity in remote locations, such as in space, and, consequently, it is highly desirable to construct a fuel cell as compact and as lightweight as possible.
A number of fuel cells are described in United States patents officially referenced and cross referenced and foreign patents and publications unofficially collected by examiners in Class 429 of the U.S. Patent and Trademark Office.
U.S. Pat. No. 3,598,657 is an example of a thin, platinum coating on a fuel cell electrode.
U.S. Pat. No. 4,125,676 is a recent example of porous fuel cells with thin catalyst layers.
U.S. Pat. Nos. 3,318,730, 3,617,385, 3,770,508, 4,031,219 and 4,128,701 are of general interest as representative of patents found in Class 429.
U.S. Pat. No. 3,787,244 describes forcing a salt of a metal catalyst through pores of a substrate to cause plating of the catalyst within the pores.
U.S. Pat. No. 3,226,719 describes the coating of a porous substrate with a metal film having the same porosity as a substrate.
U.S. Pat. No. 3,776,776 is an example of a process in which metals are coated on fuel cell electrodes.
U.S. Pat. No. 3,351,487 is an example of plating inner surfaces of fibers in a permeable membrane.
A need persists for fuel cells having extremely compact and light constructions with economical use of materials and, particularly, economical uses of catalyst.